Negative-electrode active material for electrical device, and electrical device using same

Abstract

[Problem] To provide a means for improving cycle durability in an electrical device such as a lithium-ion secondary cell. [Solution] A negative-electrode active material used in an electrical device, the negative-electrode active material comprising a silicon-containing alloy having the structure represented by chemical formula (I): SixSnyMzAa (in the formula, A represents unavoidable impurities, M represents 1 or more transition metal elements, and x, y, z, and a represent values of mass percentage, with 0 < x < 100, 0 < y < 100, 0 < z < 100, and 0 <= a < 0.5 and x + y + z + a = 100). When Fourier transform processing is performed on the basis of a lattice image of the silicon-containing alloy, the lattice image being obtained with a scanning electron microscope, a diffraction pattern is obtained, an inverse Fourier transformation is performed on the diffraction ring portion present within the diffraction pattern at a width of 0.7-1.0 when the distance between the Si tetrahedrons is set at 1.0, and when the distance between the Si tetrahedrons in the amorphous region is calculated on the basis of the obtained Fourier image, the distance between the Si tetrahedrons is 0.39 nm or more.

Description

technical field [0001] The present invention relates to a negative electrode active material for electric equipment and an electric equipment using the same. The negative electrode active material for electrical equipment of the present invention and electrical equipment using the same are used, for example, as secondary batteries, capacitors, etc., as driving power sources and auxiliary power sources for engines of vehicles such as electric vehicles, fuel cell vehicles, and hybrid electric vehicles. Background technique [0002] In recent years, in order to cope with air pollution and global warming, it is urgently desired to reduce the amount of carbon dioxide. In the automotive industry, the introduction of electric vehicles (EVs) and hybrid electric vehicles (HEVs) is expected to reduce carbon dioxide emissions, and the development of electrical equipment such as secondary batteries for driving engines holds the key to the practical use of these It's in full swing. [...

AI Technical Summary

Problems solved by technology

[0008] However, in a lithium ion secondary battery using a material alloyed with Li for the negative electrode, the expansion and contraction of the negative electrode during charge and discharge are large.

For example, the volume expansion when Li ions are stored is about 1.2 times for graphite materials, and in the case of Si materials, when Si and Li are alloyed, a larger transition occurs from an amorphous state to a crystalline state. Volume change (about 4 times), so there is a problem that the cycle life of the electrode is shortened

In addition, in the case of Si negative electrode active materials, capacity and cycle durability are in a trade-off relationship, and there is a problem that it is difficult to improve cycle durability while exhibiting high capacity.

Images